LynxOS

LynxOS was developed by Lynx Real-time Systems as a UNIX-compatible and POSIX-conforming operating system. It is designed for complex real-time applications that require fast, deterministic response as well as industry-standard compliance. It is fully preemptible, fully re-entrant and very compact. The modularity inherent in the LynxOS architecture makes the operating system highly scalable, configurable, and versatile, LynxOS can be configured to be a full-blown self-hosted target/development environment, or it can be scaled down and combined with an application to form a ROMable image for specialized embedded control applications.
LynxOS conforms to the POSIX 1003.1 system interface standard and has implemented drafts of the current POSIX 1003.1b real-time extensions and POSIX 1003.1c threads extensions. Also, LynxOS includes the AT&T System V.3 and 4.3 BSD system call interfaces and libraries, which provide a high degree of source-level application compatibility.
LynxOS Kernel Threads offer an efficient way to service interrupts while ensuring that the determinism of the overall LynxOS system remains intact. Kernel Threads reduce interrupt overhead by performing the bulk of asynchronous processing at the priority of the process that made the request, giving developers greater control over priorities of system operations (i.e. networking, disk access, etc.). Kernel Threads allow complex real-time systems to be built simply and remain predictable even when inundated with large numbers of asynchronous interrupts.
LynxOS offers industry standard net-working with NFS, TCP/IP, STREAMS, and SOCKETs. The development environment is UNIX-compatible with standard tools like rcs, yacc, ls, csh, gcc, gdb, etc. Cross-development packages are available as well as porting kits. For GUI support, LynxOS offers X11R5 and MOTIF. Standard AT perhiperals such as floppy drives, serial/parallel ports and others are supported.